On Jun 16, 2021 we had a free webinar “Gender Selection, PGD, PGS in Surrogacy and IVF Programs”.
Our guests were: Oleksii Kosenko – ADONIS’ Deputy Director of Embryology Department, Yevhen Shytikov – embryologist, and biologist, Maria Feekes – Executive Director of ADONIS Fertility International.
And in this article we share questions that were discussed.
How safe is the testing process for the embryo? Are there any precautions or situations when it is not recommended?
Of course, since it is an invasive procedure, there could be stress and a potential risk for the embryo. But because the advanced technologies went so far, the risk is very minimal.
There are different methodologies of testing itself and they can be done in different phases.
At ADONIS, we typically prefer to do PG testing on the 6th day when Trichoderma biopsy is being done and 1 to 6 cells are taken from the embryo for that.
It is also possible to do PG testing on the 3rd day, but in that case, you can only take 1 cell. So the validity of the test is being minimized significantly.
And in this case, you will have no guarantee that this embryo will become a full blastocyst.
It is not that the testing is injuring, but it is a part of developing the embryo.
It is very normal, that quantity of embryos is not the same as blastocysts. Not all blastocysts develop to the embryo stage.
What is the difference between the methodology of testing? What are NGS and FISH testing?
When we are talking about ART programs, of course, the process of creating is artificial. And we never could come 100% to what exists in nature. The industry already came as close as possible, but still, there are variations from if the embryo was created naturally within a human body.
In a natural cycle of a woman, during the ovulation, there are typically maybe 10 oocytes are being developed naturally. And through natural selection, the body of the woman herself would be making the decision which egg will be the strongest based on the level of hormone and so on.
And when we are using ART, during the egg retrieval there is an extra supply of hormones is going on. This means that all of those 10 eggs, have the potential of developing and all of them become viable even those that naturally are weaker, that naturally would be discarded and not survived. And for those eggs, it is not possible to identify visually if they are healthy genetically and do not have any deviations.
As those eggs are developing, the really weaker ones, they naturally might not develop to full blastocysts.
And of course, there is a sperm factor as well, and with the ICSI method, the best sperm morphologically is being selected. But it is not possible to do a genetic test on each sperm cell before.
So why many doctors recommend PGT, because there are some variables, that are not possible to detect in embryos even while they developing in perfect visual conditions. So that is why it is important to check hidden anapolies.
PGD is checking for full exposure of chromosomes.
The FISH methodology is faster and cheaper than NGS.
But we need to understand what is the purpose of testing. If we want to exclude those possible anomalies that developing during the first days of ART, then we recommend NGS 24 chromosomes testing. Because It allows you to do the check of full-spectrum chromosomes.
But if you know that in your condition you have a very specific chromosome anomaly that you do not want to pass to the embryo, then it is possible to use the FISH method. The methodology of FISH is more like a zond that can target a particular chromosome in this case.
So the reason the FISH method is very fast is that you can target a particular chromosome.
This method can be also used in a combination with karyotyping.
Can NGS and FISH methods be used together?
No, NGS and FISH can not be used together. The reason for that is because they are going into different laboratories. One is molecular, the other is cellular. You can not do 2 biopsies in one embryo.
What should we know about the vitrification process?
It is a relatively new process but advanced in the industry. The start of the process is to pull out the water of the embryo, so there will not be a risk of ice concentration that could erupt the embryo. Then it is being replaced with cryoprotection, which is replacing the water and creating a shell around oocytes or embryos.
It does certain stress on an embryo of course. So these protection levels are being introduced slowly in different concentrations so the embryo slowly is getting used to it. And once the embryo is protected by those cry protectors the embryo is being put into liquid nitrogen at such low temperature that all of the live processes have been paused. After that, it’s being put into a cryo carrier.
The survival percentage of embryos with the vitrification process is very high – over 99%. It is much more effective than old cryopreservation methods and it is very safe for eggs or embryos.
In comparison with sperm, vitrification is not used as a method, because there is no need to vitrify every cell. Because there is a huge quantity of sperm cells. So simple cryopreservation is being used for freezing sperm.
What is the thawing process? What are the providers? And which media do we have in our lab?
The role of the media of those elements on thawing is to extract those cry protectors that have been added in a process of vitrification. All of them contain some type of polysaccharide.
So for the thawing process, we always like to use the same media that has been used for the vitrification.
At our laboratory, we have the media that are most commonly used: Cryotec, Kitazato, Irvine, and SAGE.
The type of preferred media can depend on a country.
But basically, there are only two types of polysaccharides that are used to take out the water off the embryo in all media. The role of that sugar is just to clean and bring the water. So there are more and more studies are being done to unify the process.
How can we be sure of the safety and integrity of biomaterial?
One of the big practices that are used is double control. There is not only one person who controls the process, but a minimum of 2. Also, there are such things as labeling, digitized control, etc.
Also, it Is important from the patience side to check all the documents.
Please, check the full recording of our webinar here:
